The present invention relates to access port covering devices, and, more particularly, to an improved port covers device which includes an integral sealing member.
On modern aircraft, various access ports are provided for servicing the aircraft. In some instances, the system being serviced may leak fluids which, if permitted to escape, can freeze on the aircraft surfaces during flight. These frozen accretions can break away and may fall to earth as potentially dangerous projectiles or, what is worse, can be ingested by an aircraft engine or damage other structural parts of the aircraft.
This problem has arisen in connection with the aircraft human waste system, which includes an onboard storage tank that accumulates the lavatory waste products during flight and which is drained and cleaned by ground based service personnel. Prior art attempts at preventing leakage included the patent to W. B. Lynch, U.S. Pat. No. 3,010,694, which disclosed a removable plug and coupling assembly that provided a fluid tight seal at the servicing outlet port.
Because ground service personnel sometimes failed to replace the plug, an improved port covering device was disclosed in U.S. Pat. No. 4,127,215, to Donald L. Morrison, (assigned to the assignee of the present invention) which would not close unless the plug was in place. An improved, lightweight plug for the conduit was disclosed in U.S. Pat. No. 4,188,675 to Herbert H. Ast, (assigned to the assignee of the present invention).
In an effort to supplant the plug completely, double "flap" sealing devices were tried. One, shown in U.S. Pat. No. 4,098,427, to Milton Donald Duckworth teaches a pair of sealing doors, one of which caps the outer end of the conduit and the other of which seats against an annular flange on the interior of the conduit. An improvement over Duckworth, which permitted an unobstructed flow was disclosed in the patent to Gregory T. Elliott, U.S. Pat. No. 4,690,296, (assigned to the assignee of the present invention).
However, even the best efforts of the prior art are somehow defeated by airline servicing personnel who abuse the seals and the operating mechanisms so that even the Elliott combination occasionally experienced fluid leakage during a flight. The problem seemed to stem from some leakage from the interior which could not be retained by the seals carried on the outer door that seat against the edges of the conduit, and which are invariably damaged during servicing.